A single introduction of Yersinia pestis to Brazil during the 3rd plague pandemic

Yersinia pestiswas introduced to Brazil during the third plague pandemicand currently exists in several recognized foci. There is currently limited availablephylogeographic data regarding Y. pestis in Brazil. We generated whole genome sequencesfor 411 Y. pestis strains from six Brazilian foci to investigate the phylogeographyof Y. pestis in Brazil; these strains were isolated from 1966 to 1997. All 411 strains were assigned to a single monophyletic clade within the 1.ORI population, indicating a single Y. pestis introduction was responsible for the successful establishment of endemic foci in Brazil. There was a moderate level of genomic diversity but little population structure among the 411 Brazilian Y. pestis strains, consistent with a radial expansion wherein Y. pestis spread rapidly from the coast to the interior of Brazil and became ecologically established. Overall, there were no strong spatial or temporal patterns among the Brazilian strains. However, strains from the same focus tended to be more closely related and strains isolated from foci closer to the coast tended to fall in more basal positions in the whole genome phylogeny than strains from more interior foci. Overall, the patterns observed in Brazil are similar to other locations affected during the 3rd plague pandemicsuch as in North America and Madagascar.